Guide to 5083 O vs H116 Marine Grade Aluminum Plate - Knowledge

marine classification society certifications

In marine engineering and offshore applications, selecting the correct material is the most critical decision a naval architect can make. While Marine Grade Aluminum Plate 5083 is the globally recognized standard, a common and dangerous misunderstanding exists regarding its tempers.

Specifically, buyers often confuse the 5083-O and 5083 H116 tempers. Note: These two designations are mutually exclusive. An aluminum plate cannot be both "O" (annealed/soft) and "H116" (strain-hardened/hard) at the same time. Choosing the wrong temper will lead to manufacturing failures like cracking during bending or catastrophic structural failure in saltwater.

As a direct marine aluminum plate manufacturer, GNEE supplies fully certified 5083 plates in all major tempers. This technical guide will clarify the exact differences, explain where to use each temper, and help you specify the right material for your next shipbuilding or industrial project.

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Difference between 5083-O vs. 5083-H116 Aluminum Plate

While both are made from the same 5083 alloy block, their mechanical properties are completely different due to how they are processed at the mill.

1. 5083-O Aluminum Plate (Annealed / Fully Soft)

The Process: The "O" temper means the aluminum plate is fully annealed. It is heated to a specific temperature and then slowly cooled, which relieves all internal stress and makes the metal extremely soft and ductile.
Mechanical Properties: Yield Strength: ~125 MPa. Elongation: ≥ 16%.
When to Use a 5083-O Aluminum Plate: The O temper offers maximum formability. You MUST use 5083-O if your factory needs to perform heavy cold working, deep drawing, or bending the plate into complex cylindrical shapes. It is the standard for LNG transport tanks, chemical storage vessels, and pressure vessel heads.

2. 5083-H116 Aluminum Plate (Strain-Hardened / Marine Grade)

The Process: The "H116" temper is a high-strength, strain-hardened (cold-rolled) condition. The mill strictly controls the rolling temperature to lock the internal grain structure and provide guaranteed resistance against seawater exfoliation corrosion (flaking).
Mechanical Properties: Yield Strength: ≥ 215 MPa. Elongation: ≥ 10%.
When to Use 5083-H116 Aluminum Plate: H116 is the mandatory choice for heavy structural applications that will be submerged in saltwater. Its high yield strength is designed to withstand the immense hydrodynamic forces of ocean waves. Use 5083-H116 for ship hulls, bulkheads, decks, and offshore oil rig components.

ASTM B928 marine aluminum plate

5083-H116 Aluminum Chemical Composition and Standards

The exceptional performance of 5083 aluminum comes from its high magnesium content. GNEE adheres strictly to international standards like ASTM B209 and ISO 6361 to ensure every plate meets these chemical limits.

Element	Content (%)	Role in the Alloy
Magnesium (Mg)	4.0 – 4.9	Primary strengthening agent; provides marine corrosion resistance.
Manganese (Mn)	0.4 – 1.0	Increases toughness and stabilizes the grain structure.
Chromium (Cr)	0.05 – 0.25	Prevents stress corrosion cracking (SCC).
Iron (Fe) & Silicon (Si)	≤ 0.4 each	Strictly limited to prevent brittleness.
Aluminum (Al)	Balance	Base metal.

Core Functions and Applications of 5083 Aluminum

By replacing heavy marine steel with 5083 aluminum, vessels drastically reduce their weight, which lowers fuel consumption and increases top speeds.

Shipbuilding: Hulls, decks, superstructures, and keels for commercial ferries, naval patrol boats, and luxury yachts. (Specify H116 or H321).
Offshore Platforms: Structural walkways, helipads, and accommodation modules where maintenance-free anti-corrosion materials are essential. (Specify H116 or H321).
Cryogenic & Pressure Vessels: LNG (Liquefied Natural Gas) transport tanks and chemical storage containers. 5083 performs exceptionally well at sub-zero temperatures without becoming brittle. (Specify O-temper for formability).
Heavy Transportation: Fuel tanker trucks and railway carriages. (Specify O or H111 for bending).

CCS Certified 5083 H116 Marine Aluminum Sheet

Class Certifications and the Importance of MTC

For any marine or pressure vessel application, uncertified metal is unusable. GNEE provides fully traceable plates backed by major international classification societies.

Marine Approvals: We supply DNV certified aluminum 5083, alongside ABS, LR, BV, KR and CCS certifications.
Mill Test Certificate (MTC): Every plate is shipped with an EN 10204 3.1 or 3.2 MTC, verifying the exact chemical composition, tensile/yield strength results, and successful completion of marine corrosion tests (ASTM G66).

Critical Safety Warning: Due to its high magnesium content, never use 5083 aluminum in continuous service environments where temperatures exceed 65°C (150°F). High heat causes the magnesium to precipitate to the grain boundaries, which destroys the plate's corrosion resistance and leads to catastrophic stress corrosion cracking.

Partner with GNEE as Your 5083-O Aluminum Plate Supplier

Whether you need highly formable sheets for tank fabrication or high-strength certified plates for a new vessel build, GNEE is your direct manufacturing partner. We supply standard marine dimensions (e.g., 2000mm x 6000mm) and custom thicknesses ranging from 3mm up to 200mm.

Get Your Precise Material Quote Today

Do not risk your project with incorrectly specified materials. Are you looking for a reliable supply chain to keep your factory running on schedule?
Contact GNEE today. Send us your required thickness, temper (O, H116, H321, etc.), dimensions, and total tonnage. Our technical sales engineers will provide an exact quote within 24 hours.

5083 h116 marine aluminum plate

5083 h116

FAQ

Q1: What is the difference between 5083 H116 and H321 aluminum?

A: In terms of mechanical strength and corrosion resistance, they are identical and interchangeable for shipbuilding. Both pass the same strict ASTM B928 marine tests. The only difference is the mill manufacturing route: H116 relies on controlled strain-hardening, while H321 uses strain-hardening followed by a low-temperature thermal stabilization process.

Q2: Can I bend a 5083 H116 aluminum plate like I bend 5083-O?

A: No. 5083 H116 is strain-hardened and much less ductile than the O-temper. It has a much larger minimum bend radius. If you try to bend H116 too tightly (like you would with O-temper), it will crack along the bend line. You must use O-temper for heavy-forming applications.

Q3: Does 5083 H116 aluminum need to be painted to prevent rust?

A: No. The bare aluminum naturally forms a dense oxide layer that blocks chloride ions in seawater from penetrating the metal. You do not need protective paint for corrosion resistance. However, shipyards universally apply copper-free anti-fouling paint below the waterline to stop marine life (like barnacles) from attaching to the hull and causing drag.

Q4: Will welding destroy the strength of 5083 H116 plates?

A: Welding any cold-worked aluminum will reduce the strength in the immediate Heat-Affected Zone (HAZ) back to the annealed (O-temper) condition. However, 5083 has the highest annealed strength of any non-heat-treatable alloy. Naval architects always factor this HAZ strength into the hull blueprint, ensuring the vessel remains completely safe. Always use ER5183 or ER5356 filler wire.

Q5: What is the typical lead time for DNV- or ABS certified plates from GNEE?

A: For standard marine dimensions, GNEE holds a large inventory for fast dispatch (typically 7-10 days). If your shipyard requires custom heavy rolling or an on-site third-party class surveyor (like an ABS or DNV inspector) to stamp a specific batch, production and certification typically take 25 to 35 days.